Method of securing tube end portions in bores of a heavy plate by pilgrim step rolling



J1me 1969 M. HAUSCHKE ETAL 3,449,812

METHOD OF SECURING TUBE END PORTIONS IN BORES O1" Hl'I/aVY PLATE BY PILGRIM STEP ROLLlNU Filed Jan. 23, 1967 Fig. I

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United States Patent f 3,449,812 METHOD OF SECURING TUBE END PORTIONS EN BORES OF A HEAVY PLATE BY PTLGRHVI STEP ROLLING Manfred Hauschke, Remscheid, and Erich Ebbinghaus, Remscheid-Hasten, Germany, assignors to Kotthaus & Busch K.G., Remscheid, Germany Filed Jan. 23, 1967, Ser. No. 611,006 Claims priority, application Germany, Jan. 24, 1966,

Int. or. nine 21/00 US. Cl. 29---157.4 7 Claims ABSTRACT OF THE DISCLOSURE A method for securing tube end portions in bores of a heavy plate by rolling in which roller means comprising a conical mandrel and rollers distributed about the mandrel and in engagement therewith and having axes inclined to the axis of the mandrel are inserted in the end portion of a tube extending through a bore in the heavy plate, whereupon the mandrel is rotated in one direction about its axis to cause thereby a rotation of the rollers and advance of the conical mandrel relative to the rollers as well as advance of the latter relative to the tube so as to press the rollers against the inner surface of the tube to gradually expand the latter, whereby the moment for rotating the mandrel increases. The increasing moment is measured and the direction of rotation of the mandrel is automatically reversed for a predetermined time when the measured moment reaches a predetermined maximum, whereby the mandrel and rollers are retracted for a given distance. After the predetermined time has passed, the mandrel is again rotated in the first mentioned direction to advance the mandrel and rollers again and to initiate the next rolling step. The last two steps are repeated until the whole tube end located in the bore is expanded in tight engagement with the bore surface.

Background of the invention The present invention relates to a method for securing tube end portions in respective bores of a heavy plate by a rolling process in which roller means, comprising a conical mandrel and rollers distributed about the axis of the mandrel in engagement with the outer surface thereof and having axes inclined to the axis of the mandrel, are inserted in the tube end portion, whereupon the mandrel is rotated to advance the roller means while its rolling diameter is increased to expand the tube end portion in tight engagement with the bore surface.

Tube end portions sometimes have to be secured by rolling into bores of heavy plates, which may have a thickness of 100 to 700 mm. To uniformly expand the tube end portions in proper tight engagement with bores through such heavy plates is connected with considerable difficulties, since the diameter of the bores through the heavy plates sometimes are not uniform through the whole length of the bores. The outer ends of the bores are usually slightly conical and there are also minor differences in the bore diameter throughout the length of the bore. This may be due to slight variations in the hardness of the plate material or it may be due to a nonuniform discharge of the borings during the boring process. Likewise, the tube to be rolled-in is manufactured to certain tolerances.

A rolling process is known in which the rolling-in of the tube is performed in successive overlapping steps whereby of the tolerances of bore and tube is considered at each step. This known method has the disadvantage that it is extremely cumbersome and therefore expensive and very time-consuming.

3,449,812 Patented June 17, 1969 Another method is known in which the rolling-in of the tube end portion into the bore of a plate is performed in one continuous operation. Even though this method is considerably faster than the first mentioned method it has also considerable disadvantages. In this rolling process the rolling means are adjusted to a fixed diameter. If in this case the rolling means acts on a portion of the tube having a plus tolerance, or maximum wall thickness which is located in a bore portion having a minus tolerance, that is a minimum inner diameter, the expansion of the tube portion may lead to an excessive compression of the tube material which in turn may cause a premature aging thereof, which during application of pressure to the interior of the tube during use may lead to dangerous crack formations in the tube. On the other hand, if the bore of the plate has a plus tolerance while the wall thickness and diameter of the tube has a minus tolerance, the expansion of the tube to la fixed diameter will not lead to the necessary tight engagement of the expanded tube with the bore surface.

It is an object of the present invention to overcome these disadvantages of methods known in the art for securing tube end portions in bores of a heavy plate by rolling.

It is another object of the present invention to provide for a rolling process of the aforementioned kind in which the tube is propertly expanded in tight engagement with the inner bore surface without excessively compacting the tube material and regardless of the direction of the tolerances of bore and tube.

Summary of the invention A method for securing tube end portions in bores of a heavy plate by rolling, comprising the steps of inserting the tube end portions respectively in the bores of the plate; inserting roller means comprising a conical mandrel and rollers distributed about the mandrel and in engagement with the outer surface thereof and having axes inclined to the axis of the mandrel into the end portion of a tube; rotating the mandrel about its axis in one direction to cause thereby rotation of the rollers about their axes and advance of the conical mandrel relative to said rollers and of the latter relative to said tube so as to press the rollers against the inner surface of the tube to gradually expand the latter in tight engagement with the bore surface, whereby the necessary moment for rotating said mandrel increases; measuring the increasing moment necessary for rotating the mandrel; automatically reversing the direction of rotation of the mandrel for a predetermined time when the measured moment reaches a predetermined moment to thereby retract mandrel and rollers for a given distance; automatically rotating the mandrel again in said one direction after said predetermined time has passed to advance the mandrel and the rollers again; and repeating the last two steps until the whole tube end portion is expanded into tight engagement with the surface of the bore in the plate.

The predetermined time during which the mandrel is rotated in the opposite direction is preferably adjustable and this time period may be adjusted to be between onetenth and ten seconds.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.

Description of the preferred embodiment FIGS. 1 and 2 schematically illustrate apparatus which may be used for carrying out the method of the present invention and application of this apparatus for expanding end portions of tubes 3 which are loosely inserted in corresponding bores 2 of a heavy plate 1 into tight engagement with the bore surfaces so as to secure the tube end portions to the plate 1. As illustrated in FIG. 2, the apparatus for carrying out the method of the present invention may include roller means comprising a sleeve 4 provided in the front end portion with a plurality of cutouts in which rollers 14, for instance three, are respectively located to be turnable about their axes and movable in radial direction toward and away from the axis of the tube 4. As can be seen from FIG. 2, the :axis of each roller 14 extends inclined at a slight angle to the axis of the sleeve 4. Coaxially arranged in the tube 4 is a conical mandrel 11 turnable about its axis relative to the tube 4 and movable relative thereto also in axial direction. The rollers 14 are arranged to engage the outer surface of the conical mandrel 11. The right end of the sleeve 4, as viewed in FIG. 2, is inserted in a cylindrical portion of a housing of a drive motor 6 (FIG. 1) coaxial with the axis of the drive shaft of the latter until the flange 12 labuts against a housing and face and so that the square end 16 of the mandrel is located in a corresponding square bore of the drive shaft of the motor to be driven thereby while being movabale in axial direction relative thereto.

When the roller means 4, 11 and 14 are inserted, for instance in the right end, as viewed in FIG. 2,'of a tube 3 [and the mandrel 11 is rotated about its axis in counterclockwise direction, the rollers 14 engaging the peripheral surface of the mandrel will be rotated in clockwise direction and due to the inclination of the axes of the rollers 14 to the axis of the mandrel 11 and to the axis of the tube 3, the roller means will be automatically advanced relative to the tube 3 toward the left, as viewed in FIG. 2, the mandrel 11 will be advanced likewise to the left relative to the rollers 14 so that the latter are continuously pushed in radially outward direction to expand thereby the inner diameter of the tube 3 as indicated at 15 and to press the outer surface thereof in tight engagement with the bore surface. The force necessary for expanding the tube will produce a counter moment on the drive motor 6 which will rise with increasing diameter of the roller means. When an increasing moment is applied to the electromotor 6 the latter will draw an increased current. Current'is supplied to the electric motor 6 from a source not shown in the drawing via a control apparatus 8 and conductor 7 connecting the control apparatus with the motor. The control apparatus 8 is constructed in a known manner to measure the current drawn by the electromotor 6 and to automatically reverse the direction of rotation of the motor when the drawn current reaches a predetermined maximum, that is when the moment exerted on the motor reaches a predetermined limit. The current at which the rotation of the motor is automatically reversed may be adjusted in a known manner by turning the knob 9 on the control apparatus 8 to a predetermined position indicated on the scale surrounding the knob and this adjustment will be made depending on the wall thickness of the tube and the material thereof.

During rotation of the mandrel in opposite direction, the roller means will be automatically retracted toward the right, as viewed in FIG. 2, and at the same time the mandrel 11 will be retracted relative to the rollers 14 so that the latter can move inwardly toward the axis of the mandrel. The rolling process and expanding of the tube 3 is thereby interrupted. The reverse rotation of the mandrel 11 is maintained for a predetermined time period and after the latter has expired a timer, not shown in the drawing and which may be incorporated in the control apparatus 8, automatically reverses again the rotation of the mandrel 11 so that the latter is rotated again in counterclockwise direction whereby the mandrel 11'is advanced relative to the rollers 14 again towards the left, as viewed in FIG. 2, and the rollers are again pressed against the inner surface of the tube and automatically advanced relative thereto so that expansion of the tube 3 is continued until the drive moment again reaches the maximum amount set by the control apparatus, whereafter the aforementioned steps are automatically repeated. The aforementioned timer may be set for a period of one-tenth to 10 seconds during which time period the roller means are withdrawn.

The aforementioned steps of automatically advancing the roller .means while simultaneously automatically expanding the active diameter thereof and of automatically retracting the roller means while automatically decreasing the active diameter thereof are repeated until the tube end portion located in the bore the plate 1 is expanded over the whole thickness of the plate. The number of necessary steps will not be the same for a given plate thickness. Evidently, when the rollers 14 act on a portion of the tube 3 having a larger wall thickness than adjacent portions thereof, or when the rollers act on a portion of the tube which is located in a bore portion having a minus tolerance, the maximum counter moment produced during expansion of the tube into tight engagement with the bore surface will be reached sooner than in the case in which the tolerances of tube or bore go to the other side. The time, however, in which the roller means are retracted is always the same, since this time is automatically fixed by the aforementioned timer. The length of each forward rolling step will depend on when the desired expansion of the tube necessary to bring the same into tight engagement with the bore surface is reached. Since each forward step is automatically interrupted when the force for expanding the tube exerts a predetermined counter moment on the drive motor, the process of the present invention will assure that exertion of excessive expansion forces onto the tube is definitely prevented. Evidently, the portions of the inner surface of the tube which are rolled during each rolling step will overlap so that an entirely smooth inner surface of the tube will be obtained at the end of the rolling process. At the end of the rolling process the roller means can be easily retracted from the interior of the tube when the drive motor is switched off at the end of a retracting step. In carrying out the method .according to the present invention, the tubes 3 are respectively inserted into the bores 2 of the plate 1. The knob 9 of the control apparatus is then adjusted to a desired position corresponding to the diameter, the wall thickness and the material of the tube to be rolled in, the timer is adjusted for the desired retraction period, and then the roller means 4, 11 .and 14 are inserted in a respective tube end portion. The motor 6 is then started by means of the switch 10 and from there on the method according to the present invention of expanding the tube end portion into the desired tight engagement with the surface of the respective bore will proceed automatically in the manner as described above. After the end portion of one tube has been expanded through the whole thickness of the plate 1, the motor is switched off during the last retracting step and the roller means are retracted manually from the properly expanded tube end portion and then inserted into the next tube.

While the method has been described above as being carried out by advancing the roller means from the free end, or the right end of the tube ,as shown in FIG. 2, it is also possible to stepwise expand the tube by starting expansion thereof distant from the free end of the tube, that is from the left side of the plate, as viewed in FIG. 2. In this case, the roller means have to be constructed slightly diflerently than shown in FIG. 2, especially the mandrel has to taper toward the right side, as viewed in FIG. 2.

It will be understood that each of the steps described above, or two or more together, may also find useful applications in other methods of rolling differing from the methods described above.

While a specific apparatus for carrying out the method of the present invention has been illustrated and described, it is not intended to limit the method to the details of the apparatus shown since different apparatus may also be used for carrying out the method of the present invention without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific .aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.

We claim:

1. A method for securing tube end portions in bores of a heavy plate by rolling comprising the steps of inserting the tube end portions respectively in the bores of the plate; inserting roller means comprising a conical mandrel and rollers distributed about the mandrel in engagement with the outer surface thereof and having axes inclined to the axis of the mandrel into the end portion of a tube; rotating the mandrel about its axis in a direction so as to cause thereby rotation of the rollers about their axes and advance of the conical mandrel relative to the rollers and advance of the latter relative to said tube so as to press the rollers against the inner surface of the tube to gradually expand the latter in tight engagement with the bore surface, whereby the moment to rotate the mandrel increases; measuring the increasing moment necessary for rotating the mandrel; automatically reversing the direction of rotation of said mandrel for a predetermined time when said measured moment reaches a predetermined moment, thereby retracting m'andrel and rollers for a given distance; automatically rotating the mandrel again in said one direction after said predetermined time has elapsed to advance the mandrel and the rollers again and to initiate the next rolling step;

and repeating the last two steps until the whole end portion of the tube in the bore of the plate is expanded in tight engagement with the bore surface.

2. A method as defined in claim 1, wherein said predetermined time during which said mandrel is rotated in the reverse direction is shorter than the time during which said mandrel is rotated in said one direction.

3. A method as defined in claim 2, wherein said predetermined time is set to be between and 10 seconds.

4. A method as defined in claim 1, wherein said mandrel is driven by an electric motor, .and wherein said increasing drive moment is measured by the increase of current drawn by the motor.

5. A method as defined in claim 1, wherein said predetermined moment can be adjusted in dependence on the wall thickness of the tube and the material thereof.

6. A method as defined in claim 1, wherein the gradual expansion of the tube end portion is started from the outer free end of the tube and wherein the mandrel is constructed and rotated in said one direction during the rolling and gradual expansion of the tube to advance the mandrel in direction .away from the free end of said tube.

7. A method as defined in claim 1,' wherein the gradual expansion of the tube is started at a distance from the free end of the tube, and wherein the mandrel is constructed and rotated in said one direction during the rolling and gradual expansion of the tube to move the mandrel in direction toward the free end of the tube.

References Cited UNITED STATES PATENTS 2,089,790 8/ 1937 Halpern 29-407 2,219,784 10/ 1940 Maupin. 2,375,235 5/1945 Maxwell. 2,393,283 l/l946 Boyles. 2,409,219 10/ 1946 Maxwell. 2,737,996 3/1956 Toth.

. FOREIGN PATENTS 302,331 5 1929 Great Britain.

CHARLIE T. MOON, Primary Examiner.

US. Cl. X.R. 

